From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-13.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id D2542C433E0 for ; Thu, 25 Feb 2021 17:06:55 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 5C15E64F06 for ; Thu, 25 Feb 2021 17:06:55 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 5C15E64F06 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=linux.ibm.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id C88636B0005; Thu, 25 Feb 2021 12:06:54 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id C10DB6B0006; Thu, 25 Feb 2021 12:06:54 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id A63E58D0001; Thu, 25 Feb 2021 12:06:54 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0232.hostedemail.com [216.40.44.232]) by kanga.kvack.org (Postfix) with ESMTP id 8B2CD6B0005 for ; Thu, 25 Feb 2021 12:06:54 -0500 (EST) Received: from smtpin29.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay04.hostedemail.com (Postfix) with ESMTP id 4923C4DDF for ; Thu, 25 Feb 2021 17:06:54 +0000 (UTC) X-FDA: 77857419948.29.A437469 Received: from mx0a-001b2d01.pphosted.com (mx0a-001b2d01.pphosted.com [148.163.156.1]) by imf01.hostedemail.com (Postfix) with ESMTP id 0836C20053D0 for ; Thu, 25 Feb 2021 17:06:50 +0000 (UTC) Received: from pps.filterd (m0098410.ppops.net [127.0.0.1]) by mx0a-001b2d01.pphosted.com (8.16.0.43/8.16.0.43) with SMTP id 11PH2lAo018661; Thu, 25 Feb 2021 12:06:40 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=ibm.com; h=date : from : to : cc : subject : message-id : references : mime-version : content-type : in-reply-to; s=pp1; bh=mWpPq56z5DGoB0nelFqiqLQFXIjErs2NXFY3C+xsWTM=; b=ORgBDj9Bvj1cfNEiI1YrL8RgSkhSnNhXHxtlBk+Ut90SrNS5xhTCqdtE6nnsj7/pvCds QkZzGDWeQGV5tjaJH7MZF+N9AdSQXcEGiGvdk76rQiblgNk2TfG/IrwjoxxFaRI0iYYY blg1Ir8npSfknDPo3/cDqK0LGUni2Au6i3WY/vWhVwnB6Lt+FY0rwvmhx7K2NOXjcXB4 iuckFVoFpLa1GHY5WSsUpkw+xq4q7WqPltUEbABKQL7kQvMrR4j4o3Fn/BxsMj3e/2Rs NRyHMQoGZ/yOI11hdR88u/w5hiuFfQfaCRqpBwcImURAwFmfIYnzY+iCjdkODV4OzNna lg== Received: from pps.reinject (localhost [127.0.0.1]) by mx0a-001b2d01.pphosted.com with ESMTP id 36xfcx9bbk-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Thu, 25 Feb 2021 12:06:39 -0500 Received: from m0098410.ppops.net (m0098410.ppops.net [127.0.0.1]) by pps.reinject (8.16.0.43/8.16.0.43) with SMTP id 11PH3JEv020221; Thu, 25 Feb 2021 12:06:39 -0500 Received: from ppma03ams.nl.ibm.com (62.31.33a9.ip4.static.sl-reverse.com [169.51.49.98]) by mx0a-001b2d01.pphosted.com with ESMTP id 36xfcx9b8k-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Thu, 25 Feb 2021 12:06:39 -0500 Received: from pps.filterd (ppma03ams.nl.ibm.com [127.0.0.1]) by ppma03ams.nl.ibm.com (8.16.0.42/8.16.0.42) with SMTP id 11PH2e46026326; Thu, 25 Feb 2021 17:06:35 GMT Received: from b06cxnps3074.portsmouth.uk.ibm.com (d06relay09.portsmouth.uk.ibm.com [9.149.109.194]) by ppma03ams.nl.ibm.com with ESMTP id 36tt284mdq-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Thu, 25 Feb 2021 17:06:35 +0000 Received: from d06av24.portsmouth.uk.ibm.com (mk.ibm.com [9.149.105.60]) by b06cxnps3074.portsmouth.uk.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id 11PH6XdR31588620 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Thu, 25 Feb 2021 17:06:33 GMT Received: from d06av24.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id A26D24203F; Thu, 25 Feb 2021 17:06:33 +0000 (GMT) Received: from d06av24.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 4DE6742042; Thu, 25 Feb 2021 17:06:31 +0000 (GMT) Received: from linux.ibm.com (unknown [9.145.51.238]) by d06av24.portsmouth.uk.ibm.com (Postfix) with ESMTPS; Thu, 25 Feb 2021 17:06:31 +0000 (GMT) Date: Thu, 25 Feb 2021 19:06:29 +0200 From: Mike Rapoport To: David Hildenbrand Cc: Mike Rapoport , Andrew Morton , Andrea Arcangeli , Baoquan He , Borislav Petkov , Chris Wilson , "H. Peter Anvin" , Ingo Molnar , Linus Torvalds , =?utf-8?Q?=C5=81ukasz?= Majczak , Mel Gorman , Michal Hocko , Qian Cai , "Sarvela, Tomi P" , Thomas Gleixner , Vlastimil Babka , linux-kernel@vger.kernel.org, linux-mm@kvack.org, stable@vger.kernel.org, x86@kernel.org Subject: Re: [PATCH v7 1/1] mm/page_alloc.c: refactor initialization of struct page for holes in memory layout Message-ID: <20210225170629.GE1854360@linux.ibm.com> References: <20210224153950.20789-1-rppt@kernel.org> <20210224153950.20789-2-rppt@kernel.org> <515b4abf-ff07-a43a-ac2e-132c33681886@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <515b4abf-ff07-a43a-ac2e-132c33681886@redhat.com> X-TM-AS-GCONF: 00 X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:6.0.369,18.0.761 definitions=2021-02-25_10:2021-02-24,2021-02-25 signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 suspectscore=0 phishscore=0 mlxscore=0 spamscore=0 priorityscore=1501 impostorscore=0 clxscore=1011 malwarescore=0 adultscore=0 mlxlogscore=999 lowpriorityscore=0 bulkscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2009150000 definitions=main-2102250130 X-Rspamd-Server: rspam04 X-Rspamd-Queue-Id: 0836C20053D0 X-Stat-Signature: jggcy4eut5yafijdbwt8txm8at1zscjj Received-SPF: none (linux.ibm.com>: No applicable sender policy available) receiver=imf01; identity=mailfrom; envelope-from=""; helo=mx0a-001b2d01.pphosted.com; client-ip=148.163.156.1 X-HE-DKIM-Result: pass/pass X-HE-Tag: 1614272810-858537 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Thu, Feb 25, 2021 at 04:59:06PM +0100, David Hildenbrand wrote: > On 24.02.21 16:39, Mike Rapoport wrote: > > From: Mike Rapoport > > > > There could be struct pages that are not backed by actual physical memory. > > This can happen when the actual memory bank is not a multiple of > > SECTION_SIZE or when an architecture does not register memory holes > > reserved by the firmware as memblock.memory. > > > > Such pages are currently initialized using init_unavailable_mem() function > > that iterates through PFNs in holes in memblock.memory and if there is a > > struct page corresponding to a PFN, the fields of this page are set to > > default values and it is marked as Reserved. > > > > init_unavailable_mem() does not take into account zone and node the page > > belongs to and sets both zone and node links in struct page to zero. > > > > Before commit 73a6e474cb37 ("mm: memmap_init: iterate over memblock regions > > rather that check each PFN") the holes inside a zone were re-initialized > > during memmap_init() and got their zone/node links right. However, after > > that commit nothing updates the struct pages representing such holes. > > > > On a system that has firmware reserved holes in a zone above ZONE_DMA, for > > instance in a configuration below: > > > > # grep -A1 E820 /proc/iomem > > 7a17b000-7a216fff : Unknown E820 type > > 7a217000-7bffffff : System RAM > > > > unset zone link in struct page will trigger > > > > VM_BUG_ON_PAGE(!zone_spans_pfn(page_zone(page), pfn), page); > > > > because there are pages in both ZONE_DMA32 and ZONE_DMA (unset zone link > > in struct page) in the same pageblock. > > > > Interleave initialization of the unavailable pages with the normal > > initialization of memory map, so that zone and node information will be > > properly set on struct pages that are not backed by the actual memory. > > > > With this change the pages for holes inside a zone will get proper > > zone/node links and the pages that are not spanned by any node will get > > links to the adjacent zone/node. > > > > Fixes: 73a6e474cb37 ("mm: memmap_init: iterate over memblock regions rather that check each PFN") > > Signed-off-by: Mike Rapoport > > Reported-by: Qian Cai > > Reported-by: Andrea Arcangeli > > Reviewed-by: Baoquan He > > --- > > mm/page_alloc.c | 147 +++++++++++++++++++++--------------------------- > > 1 file changed, 64 insertions(+), 83 deletions(-) > > > > diff --git a/mm/page_alloc.c b/mm/page_alloc.c > > index 3e93f8b29bae..a11a9acde708 100644 > > --- a/mm/page_alloc.c > > +++ b/mm/page_alloc.c > > @@ -6280,12 +6280,60 @@ static void __meminit zone_init_free_lists(struct zone *zone) > > } > > } > > +#if !defined(CONFIG_FLAT_NODE_MEM_MAP) > > +/* > > + * Only struct pages that correspond to ranges defined by memblock.memory > > + * are zeroed and initialized by going through __init_single_page() during > > + * memmap_init_zone(). > > + * > > + * But, there could be struct pages that correspond to holes in > > + * memblock.memory. This can happen because of the following reasons: > > + * - phyiscal memory bank size is not necessarily the exact multiple of the > > + * arbitrary section size > > + * - early reserved memory may not be listed in memblock.memory > > + * - memory layouts defined with memmap= kernel parameter may not align > > + * nicely with memmap sections > > + * > > + * Explicitly initialize those struct pages so that: > > + * - PG_Reserved is set > > + * - zone and node links point to zone and node that span the page > > + */ > > +static u64 __meminit init_unavailable_range(unsigned long spfn, > > + unsigned long epfn, > > + int zone, int node) > > +{ > > + unsigned long pfn; > > + u64 pgcnt = 0; > > + > > + for (pfn = spfn; pfn < epfn; pfn++) { > > + if (!pfn_valid(ALIGN_DOWN(pfn, pageblock_nr_pages))) { > > + pfn = ALIGN_DOWN(pfn, pageblock_nr_pages) > > + + pageblock_nr_pages - 1; > > + continue; > > + } > > + __init_single_page(pfn_to_page(pfn), pfn, zone, node); > > + __SetPageReserved(pfn_to_page(pfn)); > > + pgcnt++; > > + } > > + > > + return pgcnt; > > +} > > +#else > > +static inline u64 init_unavailable_range(unsigned long spfn, unsigned long epfn, > > + int zone, int node) > > +{ > > + return 0; > > +} > > +#endif > > + > > void __meminit __weak memmap_init_zone(struct zone *zone) > > { > > unsigned long zone_start_pfn = zone->zone_start_pfn; > > unsigned long zone_end_pfn = zone_start_pfn + zone->spanned_pages; > > int i, nid = zone_to_nid(zone), zone_id = zone_idx(zone); > > + static unsigned long hole_pfn = 0; > > unsigned long start_pfn, end_pfn; > > + u64 pgcnt = 0; > > for_each_mem_pfn_range(i, nid, &start_pfn, &end_pfn, NULL) { > > start_pfn = clamp(start_pfn, zone_start_pfn, zone_end_pfn); > > @@ -6295,7 +6343,23 @@ void __meminit __weak memmap_init_zone(struct zone *zone) > > memmap_init_range(end_pfn - start_pfn, nid, > > zone_id, start_pfn, zone_end_pfn, > > MEMINIT_EARLY, NULL, MIGRATE_MOVABLE); > > + > > + if (hole_pfn < start_pfn) > > + pgcnt += init_unavailable_range(hole_pfn, start_pfn, > > + zone_id, nid); > > + hole_pfn = end_pfn; > > } > > + > > +#ifdef CONFIG_SPARSEMEM > > + end_pfn = round_up(zone_end_pfn, PAGES_PER_SECTION); > > + if (hole_pfn < end_pfn) > > + pgcnt += init_unavailable_range(hole_pfn, end_pfn, > > + zone_id, nid); > > We might still double-initialize PFNs when two zones overlap within a > section, correct? You mean that a section crosses zones boundary? I don't think it's that important. > This might worth documenting - also, you might want to > take some of the original comment the accompanied this code. The original comment was not exactly right, I believe the comment above init_unavailable_range() better describes what's going on there. > You should also document (in the patch description?) that node/zone spans > are not properly handled yet for such hole pfns and that this might require > care in the future. I think Link: will suffice for this. > I played a little with weird setups and expected the memap state using > page-types (well, I can't inspect the node/zone that way but at least have a > look if the memmap was initialized). No surprises. Great, thanks! -- Sincerely yours, Mike.